psychological warfarealso called psywarthe use of propaganda against an enemy, supported by such military, economic, or political measures as may be required. Such propaganda is generally intended to demoralize the enemy, to break his will to fight or resist, and sometimes to render him favourably disposed to one’s position. Propaganda is also used to strengthen the resolve of allies or resistance fighters. The twisting of personality and the manipulation of beliefs in prisoners of war by brainwashing and related techniques can also be regarded as a form of psychological warfare.

Although often looked upon as a modern invention, psychological warfare is of ancient origin. Cyrus the Great employed it against Babylon, Xerxes against the Greeks, and Philip II of Macedon against Athens. The conquests of Genghis Khan were aided by expertly planted rumours about large numbers of ferocious Mongol horsemen in his army. Centuries later, in the American Revolution, Thomas Paine’s “Common Sense” was but one of many pamphlets and leaflets used to strengthen the British-American colonists’ will to fight. With modern scientific advances in communications, however, such as high-speed printing and radio, together with important developments in the fields of public-opinion analysis and the prediction of mass behaviour, psychological warfare has become a more systematic and widespread technique in strategy and tactics, and a larger ingredient of warfare as a whole.

Most modern armies have specialized units trained and equipped for psychological warfare. Such units were a major part of the German and Allied forces during World War II and the U.S. armed forces in the Korean and Vietnam wars. The British and the Malayan government forces made extensive use of air-dropped leaflets—promising immunity to those who surrendered—to combat the guerrilla revolt in Malaya in the early 1950s. The twisting of personality and the manipulation of beliefs in prisoners of war by brainwashing and related techniques can also be regarded as a form of psychological warfareRevolutionary guerrilla warfare as espoused by its Marxist theoreticians and practitioners—notably Mao Zedong in the Chinese civil war (1928–49), Ho Chi Minh and his successors in Vietnam (1941–75), and Fidel Castro, Ernesto “Che” Guevara, and their imitators in Latin America—regarded psychological warfare as an integral part of the art of war, inseparable from conventional military operations. Within this theoretical framework, “hearts and minds”—not only of the civil population in the area of operations but also those of the enemy and of one’s own combatants—become a principal centre of gravity in operational and tactical planning and execution. This insistence on regarding psychological warfare as central to the conduct of war stands in contrast to the role of psychological warfare in major Western military establishments, where it is generally seen as supplemental and of secondary importance.

Professionally managed psychological warfare is usually accompanied by the intelligence functions of propaganda analysis and audience information. Propaganda analysis consists of the examination of the nature and effectiveness of one’s own and the competing propagandas, together with the study of the general flow of mass communications through the audiences addressed. Audience information provides concrete details about the target groups to which propaganda is directed.

Psychological warfare is sometimes divided by its practitioners into levels reflecting the areas in and the times at which the military propaganda is expected to operate. The term strategic psychological warfare is used to denote mass communications directed to a very large audience or over a considerable expanse of territory. Tactical psychological warfare, on the other hand, implies a direct connection with combat operations, the commonest form being the surrender demand. Consolidation psychological warfare consists of messages distributed to the rear of one’s own advancing forces for the sake of protecting the line of communications, establishing military government, and carrying out the administrative tasks by such a government.

The communications media most commonly used in psychological warfare are the same as those used in civilian life; radio, newspapers, motion pictures, videos, books, and magazines form a large part of the output. Leaflets are also very widely used. The World War II leaflet output of the western Allies alone, excluding the Soviet Union, was estimated to be at least eight billion sheets, and the United States and England dropped millions of leaflets, many of which were directions on how to surrender, during their conflict with Iraq in 2003. Loudspeakers are often used in the front lines; both sides used them in the Korean War.

Psychological warfare need not be subtle or sophisticated in conduct and execution. The use of atrocities to demoralize enemy populations is an age-old tactic that has never disappeared. The systematic use of mass rape and murder to force the relocation of civilians during the “ethnic cleansing” campaigns of the civil wars accompanying the breakup of Yugoslavia in the 1990s is a case in point, as were similar tactics used in Hutu massacres of minority Tutsi in Burundi in 1994.